Geological Society. 133 



given to the wire. Its elongational spiral is right-handed, 

 and its contractional spiral is left-handed. If the substance 

 is iron, the lines of magnetization become left-handed spirals ; 

 if nickel, right-handed. Now a downward current, in the 

 downwardly magnetized wire, would, by the superposition of 

 circular magnetization in the direction opposite to that of the 

 hands of a watch, cause the lines of magnetization to become 

 left-handed spirals. Hence the sudden right-handed twist 

 induces in iron a current upwards, in nickel a current down- 

 wards. Thus we have the following simple specification for 

 the directions of the induced longitudinal currents in the two 

 substances, without reference to " up " or u down." 



From any point, P, on the surface of the wire, draw same- 

 wards parallels to the current in the nearest part of the mag- 

 netizing solenoid, and to the direction of the induced longi- 

 tudinal current. Draw a helix through P making an acute 

 angle with each of these lines. This helix is of same name 

 as the elongational helix for iron, and. as the contractional 

 helix for nickel.— "W. T., Dec. 21, 1889.] 



XL Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



[Continued from vol. xxviii. p. 493.] 



November 20, 1889.— W. T. Blanford, LL.D., F.E.S., President, 



in the Chair. 



rPHE following communications were read : — 



■*■ 1. "On the Occurrence of the Striped Hyaena in the Tertiary 



of the Yal d'Arno." By E. Lydekker, Esq., B.A., F.G.S. 



2. "The Catastrophe of Kantzorik, Armenia." By Mons. F. H. 

 Corpi. 



The village is 60 kil. from Erzeroum, and 1600 metres above sea- 

 level. Subterranean noises and the failure of the springs had given 

 warning, and on 2nd August last part of the " Eastern mountain " 

 burst open, when the village, with 136 of its inhabitants, was 

 buried in a muddy mass. 



The author described the district as formed of Triassic, Jurassic, 

 and Cretaceous strata, subsequently broken up and torn by granitic, 

 trachytic, and basaltic rocks, which overlie or underlie the Secon- 

 dary rocks, according to the nature of the dislocation. 



The now was found to have a length from east to west of 7-8 kil., 

 with a width ranging from 100 to 300 metres, and the contents were 

 estimated at 50,000,000 cubic metres. It appeared as a mass of 

 blue-grey marly mud, which, after the escape of the gases, soli- 

 dified at the top; the inequalities projected to the extent of 10 

 metres. The site of the village was marked by an elevation of the 



